Two-degree-of-freedom vortex-induced vibration of two mechanically coupled cylinders of different diameters in steady current

Rahmanian, Mehran; Zhao, Ming; Cheng, Liang; Zhou, Tongming

doi:10.1016/j.jfluidstructs.2012.07.001

Cited by 48 publications

(14 citation statements)

References 42 publications

(19 reference statements)

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“…The SST k − ω turbulence energy model proposed by Menter [43], which can give good predictions of the boundary layer flows with adverse pressure gradients, is applied for closing the RANS equations [42,44]. This model approximates the eddy viscosity using the kinetic energy (k) and its specific dissipation rate (ω) transport equations, which can be found in Menter [43] in detail.…”

Section: Governing Equationsmentioning

confidence: 99%

“…They found that the mean drag force and the root mean square lift force can be reduced if the small rod is placed in an appropriate position. Rahmanian et al [42] have conducted similar simulations of two-degree-of-freedom vortexinduced vibration of two mechanically coupled cylinders with a diameter ratio of 0.1. The gap ratio and the angular position of small rod when the maximum and minimum vibration amplitudes occur are identified.…”

Section: Introductionmentioning

confidence: 99%

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Numerical evaluation of passive control of VIV by small control rods

Zhu

Yao

2015

Applied Ocean Research

111

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Section: Governing Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of passive control of VIV by small control rods

Zhu

Yao

2015

Applied Ocean Research

111

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“…[15][16][17][18] VIV of multiple cylinders in flows is also investigated experimentally and numerically. [19][20][21][22][23][24][25][26] Kondo, 27 Lucor et al, 28 and Navrose and Mittal 29 simulated VIV of a circular cylinder at relatively low Reynolds numbers in the turbulent flow regime by solving the 3D Navier-Stokes equations using the Petrov-Galerkin finite element method. Oscillatory flow induced vibration is studied by many researchers due to its relevance of response of offshore cylindrical structures in ocean waves.…”

Section: Introductionmentioning

confidence: 99%

Vortex-induced vibration of a circular cylinder of finite length

Zhao

Cheng

2014

Physics of Fluids

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Vortex-induced vibration (VIV) of a rigid circular cylinder of finite length subject to uniform steady flow is investigated numerically. The study is focused on the effect of the free end on the response of the cylinder. The vibration of the cylinder is confined only in the cross-flow direction. Three-dimensional Navier-Stokes equations are solved by the Petrov-Galerkin finite element method and the equation of the motion is solved for the cylinder displacement. Simulations are conducted for a constant mass ratio of 2, a constant Reynolds number of 300 and cylinder length to diameter ratios of L/D = 1, 2, 5 10, and 20. It is found that the vortex shedding in the wake of a fixed cylinder is suppressed if the cylinder length is less than 2 cylinder diameters. However, if the cylinder is allowed to vibrate, VIV happens at L/D = 1 and 2 and the response amplitudes at these two cylinder lengths are comparable with that of a 2D-cylinder. The vortices that are shed from a short cylinder of L/D = 1 and 2 are found to be generated from the free-end of the cylinder and convected toward the top end of the cylinder by the upwash velocity. They are found to be nearly perpendicular to the cylinder span. The wake flow in a vibrating cylinder with L/D greater than 5 includes the vortex shedding flow at the top part of the cylinder and the end-induced vortex shedding near the free-end of the cylinder. The phase difference between the sectional lift coefficient and the vibration displacement near the free-end of the cylinder changes from 0° to 180° at higher reduced velocity than that near the top end. Strong variation of the flow along the cylinder span occurs at reduced velocities where the lift coefficient near the free-end and that near the top end are in anti-phase with each other.

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“…The peak amplitude and the lock-in regime of their vibration are enlarged and narrowed respectively (Zhao et al 2016). For the VIV of the two staggered cylinders, more than one lock-in regimes can be observed (Rahmanian et al 2012), and the instantaneous position of the cylinders relative to the last generated vortices has prominent effect on the force coefficients (Zhao and Yan 2013).…”

Section: Introductionmentioning

confidence: 99%

Vortex-induced vibrations of a circular cylinder with two symmetrically arranged control rods

Wang

2020

Fluid Dyn. Res.

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In this paper, the vortex-induced vibration (VIV) of a main cylinder with two symmetrically arranged control rods at Reynolds number of 500 is numerically simulated. The control rods and the main cylinder are connected rigidly and can move synchronously, which is modeled as a spring oscillator with double degree of freedom. Seven gap ratios (G/D = 0.1 ∼2) and sixteen angles (α = 15 • ∼165 • ) are used to model the cylinder system. Thirteen flow patterns are identified, and the VIV of the cylinder system in every flow pattern is discussed separately. It is found that the characteristics of the VIV of the cylinder system are similar in the same flow pattern, which may give a way to understand the VIV of the multiple cylinders further. Based on the classification in previous researches, some advanced insights into the passive control are achieved. The control rods located in the boundary layer (G/D = 0.1) can change the VIV of the main cylinder most effectively, and the effect decreases with increasing gap ratio. The control rods immerged in the wake of the main cylinder may result in sub-harmonic resonance, while the control rods located centrally in front of the main cylinder does not obviously affect the VIV of the main cylinder. As G/D = 0.1 ∼0.7, overall, the control rods located nearly side-by-side with main cylinder can amplify the VIV, while the control rods located downstream of the main cylinder can suppress the VIV. As G/D = 1 ∼2, the control rods can suppress the VIV slightly, and the effect increases with increasing gap ratio and decreasing angle. For G/D = 0.1 & α = 105 • , the VIV is magnified for maximum effect, and the peak amplitude is about twice that of the single cylinder. For G/D = 0.2 & α = 45 • , the VIV is suppressed for

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Two-degree-of-freedom vortex-induced vibration of two mechanically coupled cylinders of different diameters in steady current

Cited by 48 publications

References 42 publications

Numerical evaluation of passive control of VIV by small control rods

Numerical evaluation of passive control of VIV by small control rods

Vortex-induced vibration of a circular cylinder of finite length

Vortex-induced vibrations of a circular cylinder with two symmetrically arranged control rods

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